MEXICO CITY – A Mexican judge has authorized 40 days of detention for an alleged member of the Zetas drug cartel suspected in the killing of a U.S. immigration agent.

The Attorney General's Office says the judge's order will allow federal investigators to conduct a more thorough investigation of Julian Zapata Espinoza's alleged involvement with the drug cartel.

Zapata Espinoza is the main suspect in the Feb. 15 killing of U.S. Immigration and Customs Enforcement agent Jaime Zapata.

The office said in a statement Saturday that the judge ordered that eight other people arrested along with Zapata Espinoza also be held for 40 days. Two of them are suspected of taking part in the attack, which also wounded U.S. immigration agent Victor Avila.